446 THE IRON INDUSTRY.
furnaces making one-tenth as much. Only 85 per cent, of the Bessemer steel was rolled into rails, for at Steelton, Cambria, Bethlehem and elsewhere, considerable high-carbon steel was being made, as well as some soft steel. Some Bessemer plants not connected with rail mills were operated to make steels for special purposes and ' supply the general trade, and this development became more pronounced from 1888 to 1890, when only 63 per cent, was put into rails, while from 1891 to 1893 more than half the Bessemer output went into" miscellaneous work, and from 1894 to 1896 only one-third was used for rails.
This great change was brought about by many causes, among which was the general use of the reversing mill for rolling four-inch square billets directly from the ingot, and the immediate acceptance by the trade of that size as the standard. By the economies following this innovation wrought-iron was driven from the market and was superseded by steel. One of the most important fields affected by this change was the making of railway joints or splices, which amount to from five to seven per cent, of the weight of the rails themselves. A still greater change was the rapid and almost complete substitution of steel for plates and sheets of all kinds.
During all these years the open-hearth process has been making very heavy strides and narrowing the field of the Bessemer converter. One of the first acts of trespass was in high-carbon steels; it was found that the steel made in the regenerative furnace gave better results, and today very little high steel is made by the pneumatic method. The next encroachment was in structural shapes, where the Bessemer product found a great outlet in the years from 1885 to 1893. The converter product going into bridges is very small at present, while it is becoming less for ships and buildings. This growth of the open-hearth furnace is shown by the fact that in 1901 the steel made in the converter formed only 65 per cent, of the total output, while from. 1875 to 1890 it was about 88 per cent. It is also shown by the fact that in the two years of 1900 and 1901 the proportion of Bessemer steel used for rails increased to an average of 42 per cent., it being only 33 per cent, in 1894 to 1896.
Today two-thirds of the steel made in the "United States is Bessemer and one-third open-hearth. Practically all the rails are Bessemer, but open-hearth steel is used for almost all other work where the material is subject to physical and chemical specifications. One-